The present invention relates to rolling bearings and more particularly to ball bearings incorporating a damping means in the form of an elastically flexible element in at least one of the race rings which the rolling elements engage to produce a predetermined resistance to rolling.
Rolling bearings of the above type are used in applications where it is desirable to eliminate or minimize greatly chattering noises and other undesirable phenomena which occur as a result of radial play in the rolling bearing. Bearings of this type are typically used, for example, in automotive applications or assemblies in spring and steering suspensions. Bearings of this type are also used in machines wherein rotary vibrations superimposed on the rotary movement produce annoying effects but where an increased roller resistance can be tolerated. A typical example of a bearing of this type is in the support for printing rolls.
Rolling bearings with increased rolling element resistance are not new per se. An example of such a bearing is shown in German Pat. No. 932,942. In accordance with this arrangement, grooves are machined in the raceway and an elastic ring is inserted in the groove which slightly projects above the raceway. Accordingly, the rolling elements are subjected to a predetermined squeezing action resulting in an increased roller resistance.
These assemblies are considerably more expensive to manufacture by reason of the fact that the rings must be machined to provide the grooves. Furthermore, the raceway is weakened particularly in relation to radial loading as a result of which the application areas are severely limited compared with standard bearings of the same size and consequently larger assemblies must be used. An additional disadvantage of these known rolling bearing constructions is that during operation, the inserted elastic ring tends to elongate by reason of the squeezing action and thus the elastic ring can be transported or carried along by the rolling elements. Consequently, the bearing prematurely looses its function or even in some instances fails.
With the above in mind, it is an object of the present invention to provide a rolling bearing of the above mentioned type which eliminates the above noted disadvantages. As illustrated, the bearing comprises a pair of metal bearing rings having raceways formed therein, a plurality of rolling elements, such as balls, in the annular space between the raceways, at least one of the rings having a shoulder interrupted by at least one recess and an elastic damping element anchored in the recess having a face portion projecting into the raceway area.
Bearing races for rolling bearing in accordance with the present invention which incorporates the damping elements can be simply and inexpensively produced by shaping without machining. The recesses in the raceway shoulders or projections are filled with an elastic material such as rubber in such a way that the damping element projects into the raceway area. In this manner damping and consequent resistance of the rolling element can be simply adapted to the requirements for a given application either by variation in the degree of projection of the damping element into the raceway area or by the elastic properties of the material itself. A strong bond between the elastic damping elements and the metal of the raceways can be achieved by vulcanizing or the like. It is noted, however, the actual anchoring of the damping element is achieved by the pocket-like recesses in the annular projections defined by the raceways of the rings. Further, the damping element is frontally pressed in a peripheral direction against an axial end face or surface of shoulder sections by the roller friction as a result of which movement of the damping elements in the direction of rotation is practically excluded. Consequently, the damping element retains its full effectiveness over the entire operational life of the rolling bearing. If desired, several longer or shorter damping elements can be distributed over the periphery of the bearing. In accordance with the construction and arrangement of the damping elements, the rolling bodies or balls do not exert a rolling squeeze on the elastic material of the damping element as a result of the lateral arrangement thereof but slide along the elastic material by friction. As a result, the degree of projection of the damping elements into the raceway can be substantially reduced for a predetermined required roller resistance compared to the squeezing type construction of the prior known assemblies discussed above. Furthermore, roller resistance is produced which is practically independent of the speed of rotation of the rolling elements relative to the raceway. This is particularly important in achieving the desired resistance action from start up or stand still. In other words, in accordance with the present invention, the starting torque is substantially the same as during bearing rotation. This is particularly advantageous and important in certain environments such as suspension in automotive applications.
Other advantages of the present invention include the fact that the raceways do not require special machining or preparation for installation of the damping elements. As a result, rolling bearing with damping means in accordance with the present invention can be loaded to the same degree as the undamped standard construction. A further advantage is provided in the fabrication and the bearing mounting of the race rings. Since there is no difference except for the damping element between races for standard and damped constructions, they can be jointly produced and stored and when needed the races of the standard construction can then be provided with damping elements.
In accordance with a further feature of the present invention, at least one of the race rings has pockets or recesses provided in both shoulders on either side of the raceway. This produces a uniform damping action over the entire extent of the raceway so that all rolling elements can uniformly contribute to the total roller resistance.
Another feature of the present invention is the provision of a rolling bearing assembly incorporating damping means wherein the damping elements are interconnected by a closed, continuous annular member. In this sense the damping elements located in the pockets or recesses are connected by means of the shoulder section of the bearing race with the same elastic material so that a continuous uninterrupted closed damping ring is obtained. This produces additional friction surfaces for the rolling bodies and facilitates an approved fastening of the elastic damping assembly to the metal race ring.
If desired, auxiliary fastening means can be provided for the damping elements or damping rings. For example, small openings or grooves may be formed in the pockets or recesses in the race rings in the contact area between the elastic material which results in the provision of anchor points.